1. Field of the Invention
The present invention is generally related to an endodontic sealer, more specifically, is related to a urethane-monoacrylate resin-based endodontic sealer and the corresponding endodontic obturation material.
2. Description of the Prior Art
The purpose of root canal treatment is to create an end result where the tissues that surround a tooth's root will maintain a healthy status despite the fact that the tooth's nerve has undergone degenerative changes. Root canal treatment occurs in three stages: First comes the diagnosis. Next comes the root canal itself, in which a dentist or an endodentist (a dentist who specializes in treating the inside of the tooth) removes the pulp (and thereby the infection), and cleans the inside of the tooth preparatory to filling it, sometimes applying antibiotics to thwart further infection. A temporary filling is placed at the crown opening. Finally, in a subsequent appointment, a crown is installed to seal the tooth and protect it from further damage or infection.
Root canal obturation involves inserting a filling cone into a root canal and cementing it therein to obturate the canal using a sealer. The canal obturation material consists of a filling cone and a sealer. The common root canal filling cone material is made from gutta-percha or resilon. Root canal obturation involves inserting a filling cone into a root canal and cementing it therein to obturate the canal using a sealer. The canal obturation material consists of a filling cone and a sealer. The common root canal filling cone material is made from gutta-percha or resilon. The gutta-percha was commercialized for first time in 1887 by SS White Company, up to now already 120 years history; the ingredient of the gutta-percha includes a matrix mainly made from gutta-percha, and a filler mainly consists of zinc oxide. Resilon™ was developed by Resilon Research, the research and development team, as a new generation canal obturation material in 2004. The ingredient of Resilon™ includes a resin matrix mainly made from polycarolactone, and a filler primarily contains bioactive glass, ZnO, Tricalcium phosphate and Barium sulfate. The traditional canal obturation material mainly fall into three categories, the first kind is Zinc oxide-eugenol-based, thus has the antibacterial effect and is bio-degradable. However, it shrinks when hardens. The second kind is Calcium hydroxide-based, which is considered to be antibacterial as well as osteogenic cementogenic, but has not been firmly proven. In addition, it depends on dissolution to release the calcium ions and hydroxide ions, inevitably will lead to production of air bubbles and gaps in the obturation system. The third kind is glass ionomer-based; it was claimed to have good dentin bonding, but has been proven not as anticipated. The trend of new-generation canal obturation material is towards polymer-based materials.
The traditional root canal material is inert in nature and will not be absorbed or degraded by living tissue if the root canal is overfilled and the material extends beyond the apex. It has been a challenge for dentists to control the exact amount of the material within the border of the root canal to avoid overfilling. The cold core of the root canal material is not malleable so that it cannot be molded to the canal walls, resulting in poor adherence. In addition, when heated the root canal material cools to body temperature in the root, a uniform contraction takes place further reducing adherence to the root canal walls. Moreover, the filling is a polyisoprene rubber material in nature, which does not have the capability to bond to most dental materials, especially when the root canal sealer is a polymer-based material. Due to poor adherence and bonding, bacteria residential in the root canal can multiply or a leakage may result, causing bacteria to enter the canal from the mouth, which can lead to the persistence of an infection or other complication. Furthermore, still must request in clinical use to seal fills in the medicinal preparation material to mount thickness not be possible to be high in order to fills in root tube slit, as well as shorter polymerization time reduce technique inconvenient. According to the above, it is important to develop a novel set of root canal material which has high biocompatibility, low volume contractive rate, better chemical-bonding ability with dentinal wall and the filling and high mechanical properties.